It has been well recognized to treat water with a sulfur material such as sulfur dioxide or soluble sulfite or bisulfite salt. For example in U.S. Pat. No. 4,364,835 the dechlorination of water with such agents is discussed. More particularly there is disclosed the use of a stoichiometric excess of dechlorinating agent. This is to reduce the activity of non-volatile mutagens in the chlorinated water.
There has also been proposed to combine dechlorinating agent with comentitious substance to provide a mixture having a controlled elution of dechlorinating substance. For example it has been proposed in Japanese Patent Public Disclosure No. 55-1873 to combine a dechlorinating substance such as sodium thiosulfate and sodium sulfite with a cement constituent, e.g., gypsum and lime. The combination provides for the gradual dissolution in water of materials including the dechlorinating agent in the mixture.
There has further been proposed to provide an oxygen releasing composition that can be compacted into hard, self-supporting articles. The compaction can be handled under high pressure molding techniques, such as used for tableting. Thus a composition has been disclosed in U.S. Pat. No. 3,260,674 which lends itself to tableting operation and provides a hard tablet of non-chipping characteristic. The tablet retains its shape substantially indefinitely when immersed in water.
It would be desirable to formulate a water treating composition which not only exhibits strength and non-chipping characteristic when pressure molded, but also is free from dusting or other deleterious degradation such as can be encountered in shipping and handling. Such agent, when in molded form, should provide controlled dissolution in aqueous media. It would furthermore be most highly desirable if such composition would lend itself to present day high speed, high pressure molding technique.